Chapter 8 The space radiation environment

Abstract

In many civilian and military applications, electronic components must operate in a radiation environment, and thus may experience instability phenomena. In Section I of this chapter, we introduce the parameters which enable us: to fully characterize the particles encountered in a radiation environment and to describe their effects on matter. We then describe the two basic constituents of the environment encountered in space: solar particles and cosmic rays. Particles can be emitted by the sun, either continuously (solar wind) or sporadically (solar flares). The rest of the galaxy behaves also as a continuous source of radiation (the cosmic rays). In Section 3 we show that there exists around the Earth, zones where particles are preferentially trapped (the so-called Van Allen belts). The Earth's magnetic field is responsible for this trapping. This field also shields our planet by filtering out most of the solar and galactic particles. In the last section we show that, given some hypotheses, the radiation environment of the Earth can be modeled. The models enable us to predict the fluxes and the energy spectrum of the particles that a spacecraft will encounter during a mission in space and thus help us compute the probability that a “Single Event Phenomenon” occur or that a component fail. We finally give a few examples illustrating the use of these models.